(1) Field of the Invention
The present invention relates to a printing system and an image forming apparatus, and particularly to a fault tolerance technique that maintains normal operations of the printing system in which a plurality of print servers are used irrespective of whether a failure has occurred in any of the print servers.
(2) Description of the Related Art
Recently, in a printing system in which a print job is transmitted from a user terminal such as a personal computer (PC) to an image forming apparatus via a print server, an art has been put in practical use for speeding up image forming processing by using a load balancer to distribute print data to a plurality of print servers to reduce processing load on each of the print servers.
However, even if the processing load on each of the print server is reduced, in the case where a communication failure has occurred on a network in which user terminals, print servers, and image forming apparatuses are connected to each other, it is difficult to perform smooth image forming processing. This causes a problem that the availability of the printing system deteriorates.
In order to solve this problem, there has been proposed for example an art of checking whether or not a network failure occurs by monitoring a period necessary for transmission and reception of an e-mail via the network (for example, Japanese Patent Application Publication No. 2007-208826). According to this art, it is possible to accelerate specification of the cause for the network failure by monitoring whether or not a network failure has occurred.
Malfunction in the printing system is sometimes caused not only due to a network failure but also due to an exception event of a print server itself. There has been conventionally known an art of detecting an exception event of operating system (OS) in hardware of a print server by the print server or a monitoring system that is provided separately from the print server.
However, it is difficult to promptly deal with a failure because of no monitoring of an application level exception event relevant to primary functions of the print server. As a result, when an application level exception event has occurred, a user needs to continue to use the print server in which the exception event has occurred. This impairs the user's convenience.